The authors advance for discussion some important problems in the construction of airplanes for military use in this country. The functions of military airplanes designed for strategical and tactical reconnaissance, control of artillery fire and for pursuit are outlined. Problems in construction with reference to the two-propeller system, methods of reducing vibration, application of starting motors, details of the gasoline supply-system, metal construction for airplanes, flexible piping, desirable characteristics of mufflers, shock absorbers, landing gear, fire safety-devices, control of cooling-water temperature, variable camber wings, variable pitch propellers and propeller stresses, are all given consideration. The paper is concluded with suggestions for improvement in design relating to the use of bearing shims, the rigidity of crankcase castings, interchangeability of parts and better detail construction in the oiling, ignition, fuel supply and cooling systems.
The authors outline some of the problems that confront the automobile engineer today, showing how the demand for better performance and economy and the ever-increasing cost of volatile fuels has emphasized the necessity for thorough engineering work in the successful automobile manufacturing plant. Believing that the accurate analysis of the heat distribution in a modern automobile engine will be of great value, the authors describe a comprehensive test, made under their direction, of such an engine. This test includes measurements of the brake horsepower, friction horsepower, fuel consumption and heat losses to jackets, exhaust and cooling air. The engine tested was inclosed in a hood, similar to that used on the car in normal service and an air blast was directed through this hood at speeds approximating those at which the engine would drive a car with a given gear ratio.
It is the purpose of the author to analyze some of the factors that have influenced tractor development. He reviews a number of factors on which the usefulness of tractors depends, showing what the farmer is interested in when buying tractors and how the design should be worked out to secure the greatest general efficiency. The paper then mentions certain general specifications that are required by tractor engines. The author finds that the conditions on about 90 per cent of all farms require a four-cylinder engine of between 16 and 40 hp., operating on the four-stroke cycle. The disadvantages of the two-cylinder horizontal-opposed engine are summarized. An empirical formula is given that can be used to calculate the most satisfactory operating speed of an engine. In concluding the paper a number of the most important general themes of design are outlined. Particular mention is made of the lubrication system and of the special provisions required for kerosene burning engines.